Antenna and frequency diversity receiving apparatus

ABSTRACT

To adjust an antenna and frequency diversity receiving apparatus comprising n antennas (A 1 -An) and using m receiving frequencies to the best antenna frequency combination each of the n antennas (A 1 -An) there is assigned an IF stage (Z 1 -Zn). A quality signal (Q 1 -Qnm) representing the receiving quality will be generated for each of the n×m possible antenna frequency combinations within the IF stages (Z 1 -Zn). A digital signal processor (DS) determines by comparing the best antenna frequency combination out of the n×m quality signals (Q 1 -Qnm). The selected antenna (A 1 ) will be switched to the digital signal processor (DS) via a multiplex switch (M), and the assigned IF stage (Z 1 ) is tuned to the determined receiving frequency.

Method for selecting one of n antennas and one of m alternative receiving frequencies in an antenna and frequency diversity receiving apparatus as well as antenna and frequency diversity receiving apparatus

The invention regards to a method for selecting one of n antennas and one of m alternative receiving frequencies in an antenna and frequency diversity receiving apparatus.

Further, the invention regards to an antenna and frequency diversity receiving apparatus for selecting one of n antennas and one of m alternative receiving frequencies.

An antenna and frequency diversity receiving apparatus is a radio receiving apparatus having a radio receiver being connectable to one of several, most specially separated antennas and being tuneable to one of several alternative receiving frequencies. Antenna and frequency diversity receiving apparatuss are put to use e. g. in motor vehicles. Window antennas are preferably used as antennas, which are integrated e. g. in the windows of the motor vehicles. A selection circuit selects according to prescribable criteria one of the antennas to be connected to the radio receiver in operation of the antenna and frequency diversity receiving apparatus, for example a radio broadcasting apparatus, a television brosdcasting apparatus or a telephone equipment. An evaluation means selects one of the alternative receiving frequencies to which the radio receiver will be tuned. In order to get best possible reception, it is necessary, to find the best antenna frequency combination.

Therefore, it is an object of the invention, to create a method for an antenna and frequency diversity receiving apparatus as well as an antenna and frequency diversity receiving apparatus in such a way that the best antenna frequency combination will be as quickly and reliably as possible found out of the antennas of the receiving apparatus and of the receiving frequencies being available.

This object will be solved procedural with features given in claim 1 or 2, especially by setting all n×m possible antenna frequency combinations, to determine the receiving quality of each of the n×m possible antenna frequency combinations, by comparing the n×m determined receiving qualities against one another, and by selecting the one antenna frequency combination having the best receiving quality.

This object will be solved regarding an apparatus by features given in claim 7, especially in such a way, that each of the n antennas is connected to the input of an IF (Intermediate Frequency) stage assigned to it, in that the IF output of the n IF stages are connected with the n inputs of a multiples switch, the output of which is connected with the input of an analog-to-digital converter, in that the output of the analog-to-digital converter is connected with the input of a digital signal processor, the output of which is connected to a demodulator, in that each IF stage provides a quality output at which a quality signal representing the receiving quality can be tapped, in that the quality outputs of the n IF stages are connected with n quality inputs of the digital signal processor, in that each one controlling output of the digital signal processor is connected to each one controlling input of the n IF stages for setting the receiving frequency, and in that a controlling output of the digital signal processor is connected with the controlling input of the multiplex switch.

The inventive method provides that the receiving quality can be measured of each antenna in combination with each of the m available receiving frequencies in an antenna and frequency diversity receiving apparatus having n antennas. Therefore, all n×m possible antenna frequency combinations are provided and the receiving quality will be determined for each of these combinations. The one antenna frequency combination will be adjusted, which provides the best receiving quality.

An embodiment of the invention provides an IF stage for each antenna. The outputs of the IF stages are connected to the inputs of a multiplex switch, the output of which is connected to the input of an analog-to-digital converter. The output of the analog-to-digital converter is connected with the input of a digital signal processor, to the output of which there is connected a demodulator. For example the demodulator can be integrated in the digital signal processor, too.

Each of the n IF stages will be tuned to each of the receiving frequencies. The receiving quality will be determined for each receiving frequency and will be analysed in the digital signal processor determining the antenna frequency combination having the best receiving quality. The digital signal processor switches the antenna found to the input of the analog-to-digital converter via the multiplex switch and tunes the corresponding IF stage to the receiving frequency found.

The inventive method and the inventive antenna and frequency diversity receiving apparatus are described and explained in more detail by way of embodiments shown in the figures.

According to FIG. 1 each of the n antennas A1-An is connected to the input of an If stage Z1-Zn assigned to it. The outputs of the n IF stages Z1-Zn are connected with the inputs of a multiplex switch M, the output of which has been connected with the input of an analog-to-digital converter AD. The output of the analog-to-digital converter AD is connected with the input of a digital signal processor DS, to the output of which is connected a demodulator DM. At each IF stage Z1-Zn there is provided a quality output, at which a quality signal Q1-Qn can be tapped, representing a degree of the receiving quality. These quality outputs of the IF stages Z1-Zn are connected to quality inputs of the digital signal processor DS. The n frequency outputs F1-Fn of the digital signal processor DS are connected with the tuning inputs of the IF stages. The switch output of the digital signal processor DS is connected with the controlling input of the multiplex switch M.

The digital signal processor DS tunes each of the n IF stages Z1-Zn to each of the m alternative receiving frequencies, that all n×m antenna frequency combinations are provided. Each IF stage Z1-Zn produces a quality signal Q1-Qnm for each of the m alternative receiving frequencies. Therefore, n×m quality signals Q1-Qnm are generated, the quality signals being compared with each other and analysed in the digital signal processor. The digital signal processor ascertains with the help of the n×m quality signals Q1-Qnm the one antenna frequency combination, which provides the best receiving quality. The digital signal processor switches the multiplex switch M to the found antenna, e. g. the antenna A1, and tunes the corresponding IF stage, e. g. the IF stage Z1, to the receiving frequency found. Therefore, the digital signal processor DS receives its receiving signal from the one antenna frequency combination, distinguished by the best receiving quality among all possible antenna frequency combinations.

A feedback of the IF signals is not necessary, because the receiving quality will be ascertained already in the IF stages Z1-Zn.

The best receiving frequency can be ascertained e. g. in well known manner by quality evaluation of the IF signal for the different alternative receiving frequencies.

The digital processing of the IF signal within the digital signal processor DS provides the advantage that the generating of a retuning signal will be comparatively easy. Furthermore, interferences caused by retuning operations can be suppressed or resampled in an easy manner.

Within each IF stage Z1-Zn there is provided a mixer, a phase loop control circuit and a mixer oscillator.

The IF stages are integrateable in a module as integrated circuits in a preferred manner. Preferably, the IF stages Z1-Zn, the multiplex switch M, the analog-to-digital converter AD, the digital signal processor DS and the demodulator DM are integrated in a single module.

A further advantage of the invention can be gathered in the fact that a receiver comprising a receiving antenna can be expanded to the inventive antenna and frequency diversity receiving apparatus in a simple manner.

FIG. 2 shows an second embodiment. Elements shown and described in FIG. 1 are like in FIG. 1 and without new description. In the main, only different elements are described in the following.

According to one aspect of this second embodiment quality signals Q1, Q2 . . . Qn are set to the digital signal processor DS via a quality signal switch QM coupling in each moment one of the quality signals Q1, Q2 . . . Qn as a quality signal Q to the digital signal processor DS. The digital signal processor DS controls quality signal switch QM via a control signal QC coupled from an quality signal control output to quality signal switch QM. Therefore, it is not necessary to provide a digital signal processor DS comprising n quality signal inputs but only one quality signal input.

According to another aspect of this second embodiment there is coupled only one frequency output F via a frequency switch FS to the frequency inputs F1, F2 . . . Fn of the individual IF stages Z1, Z2 . . . Zn. To control the frequency switch FS the digital signal processor DS provides a frequency control signal via a frequency control output F to a frequency switch control input.

According to a preferred embodiment each IF stage Z1, Z2, . . . Zn comprises an IF stage memory ZM for storing among others the frequency to be used by the corresponding IF stage until receipt of another frequency value via frequency switch FS. Therefore, it is possible to use a frequency value determined as best frequency value at an earlier determining cycle.

According to another embodiment, not shown in FIG. 2, frequency switch could be replaced by an frequency splitter splitting frequency output line F to a plurality of frequency lines F1, F2 . . . Fn connecting one output F of the digital signal processor DS with the frequency inputs of all IF stages. According to this embodiment the digital signal processor DS provides all IF stages at one moment with the same frequency F.

Therefore, antenna and frequency diversity receiving apparatus provides a digital signal processor having a frequency control output which is coupled with each one of the control inputs of the n IF stages Z1-Zn via a plurality of n frequency outputs at the digital single processor DS or, alternatively, via only one frequency output of the digital signal processor DS and in addition a frequency control means FS. Frequency control means could be frequency switch FS of FIG. 2 or only a simple line splitter.

First embodiment describes a method and apparatus providing a digital signal processor comprising n frequency outputs to supply the n IF stages with each one frequency value or frequency signal. Within m steps every IF stage will be provided with the m possible frequency values to determine m quality values Q1 . . . Q1m, . . . , Qn . . . Qnm quality signals Q1, . . . Qnm.

According to another embodiment it would be also possible, to provide all or individual IF stages Z1, . . . Zn with only some of all possible frequency values. Accordingly, only corresponding quality signals would be determined. To get same number of n×m quality signals or values of such quality signals it would be possible to calculate missing values e. g. by interpolating.

List of Reference Numbers:

-   AD analog-to-digital converter -   A1-An antenna -   DM demodulator -   DS digital signal processor -   F1-Fn frequency output -   M multiplex switch -   Q1-Qnm quality signal -   ZF1-ZFn IF signal -   Z1-Zn IF stage 

1. Method for selecting one of n antennas (A1-An) and one of m alternative receiving frequencies in an antenna and frequency diversity receiving apparatus, characterized in that all n×m possible antenna frequency combinations are set to determine the receiving quality of each of the n×m possible antenna frequency combinations, in that the n×m determined receiving qualities are compared one to another, and in that the antenna frequency combination with the best receiving quality will be selected.
 2. Method for selecting one of n antennas (A1-An) and one of m alternative receiving frequencies in an antenna and frequency diversity receiving apparatus, characterized in that a plurality of n×m possible antenna frequency combinations are set to determine the receiving quality of each of the n×m possible antenna frequency combinations, in that receiving qualities of possible antenna frequency combinations which have not been determined are calculated, especially interpolated, in that the determined and calculated receiving qualities are compared one to another, and in that the antenna frequency combination with the best receiving quality will be selected.
 3. Method according to claim 1, characterized in that to each antenna (A1-An) there will be assigned an IF stage (Z1-Zn), in that each IF stage (Z1-Zn) generates an IF signal (ZF1-ZFn) out of the antenna signal of the antenna (A1-An) connected to it, in that each IF stage (Z1-Zn) generates a quality signal (Q1-Qnm) representing the receiving quality out of the antenna signal of the antenna (A1-An) connected to it, in that within a digital signal processor (DS) there are compared each to another and analyzed the n×m quality signals (Q1-Qnm) representing the receiving quality, in that the digital signal processor (DS) ascertains the antenna frequency combination having the best receiving quality out of the n×m quality signals (Q1-Qnm) representing the receiving qualities, in that the digital signal processor (DS) connects the output of the IF stage (Z1) delivering the best receiving quality via a switch (M), especially a multiplex switch (M) with the input of an analog-to-digital converter (AD) a digital output signal of which will be supplied to the input of the digital signal processor (DS), and in that the signal at the output of digital signal processor (DS) will be supplied to a demodulator (DM).
 4. Method according to claim 3, characterized in that the IF signals (ZF1-ZFn) are digitalized.
 5. Method of claims 3, characterized in that for each IF stage (Z1-Zn) there is provided a mixer, a phase loop control circuit and a mixer oscillator.
 6. Method of claim 3, characterized in that the IF stages (Z1-Zn) are built as integrated circuit.
 7. Method of claim 1, characterized in that the values of the receiving qualities are digitalized as quality signals (Q1-Qnm).
 8. Antenna and frequency diversity receiving apparatus for selecting one of n antennas (A1-An) and one of m alternative receiving frequencies, characterized in that each of the n antennas (A1-An) is connected to the input of an IF stage (Z1-Zn) assigned to it, in that the IF outputs (ZF1-ZFn) of the n IF stages (Z1-Zn) are connected with the n inputs of a switch, especially a multiplex switch (M) the output of which is connected with the input of an analog-to-digital converter (AD), in that the output of the analog-to-digital converter (AD) is connected with the input of a digital signal processor (DS) to the output of which there is connected a demodulator (DM), in that there is provided at each IF stage (Z1-Zn) a quality output, at which a quality signal (Q1-Qnm) representing the receiving quality is retrievable, in that the quality outputs of the n IF stages (Z1-Zn) are connected with n quality inputs of the digital signal processor (DS), in that at least one control output (F1-Fn) of the digital signal processor (DS) is coupled with each one control input of the n IF stages (Z1-Zn) for setting the receiving frequency, and in that a switch output of the digital signal processor (DS) is connected with the control input of the multiplex switch (M).
 9. Antenna and frequency diversity receiving apparatus according to claim 8, characterized in that a control output (F) of the digital signal processor (DS) is coupled with each one of the control inputs of the n IF stages (Z1-Zn) via a frequency control means (FS, FC) for setting the corresponding receiving frequency.
 10. Antenna and frequency diversity receiving apparatus according to claim 8, characterized in that the digital signal processor (DS) provides each one control output (F1-Fn) coupled with a corresponding control input of each one of the n IF stages (Z1-Zn) for setting the receiving frequency.
 11. Antenna and frequency diversity receiving apparatus of claim 8, characterized in that in each IF stage (Z1-Zn) there is provided a mixer, a phase loop control circuit and a mixer oscillator.
 12. Antenna and frequency diversity receiving apparatus according to claim 11, characterized in that the IF stages (Z1-Zn) are integrated in a module.
 13. Antenna and frequency diversity receiving apparatus of claim 8, characterized in that within a module there are integrated the IF stages (Z1-Zn), the multiplex switch (M), the analog-to-digital converter (AD), the digital signal processor (DS), and the demodulator (DM). 